a) Field of the Invention
The present invention relates to a triple axle suspension for use in a vehicle having a frame below which a front axle, a medium axle and a rear axle are mounted in a triple axle relationship.
b) Brief Description of the Prior Art
Triple axle suspensions for use to equalize the load over three adjacent axles of large vehicles such as trucks or semi-trailers, are already known. In support of this contention, reference can be made, by way of non-restrictive examples, German patent No. 520,672 of 1931 and to U.S. Pat. Nos. 2,032,721 of 1936; U.S. Pat. No. 2,821,408 of 1958; U.S. Pat. No. 3,219,360 of 1965; U.S. Pat. No. 3,762,487 of 1973 and U.S. Pat. No. 4,813,695 of 1989.
In such a suspension, it is of common practice to use equalizers that are rockably mounted under the frame of the vehicle and connected to springs supporting the axles in such a manner as to distribute unequal loading of any axle to all the axles of the triple axle suspension, in particular when the vehicle moves on an uneven road or trail or passes over a bump. Once again, reference can be made to the above-mentioned patents.
In the field of vehicle suspensions, it is also known to use rigid beams to support the axles of the vehicle, instead of using springs (see, for example, U.S. Pat. No. 3,219,360 mentioned hereinabove). However, in such a case, other means must be provided to  less than  less than absorb greater than  greater than  the up and down motions of the axles when the vehicle is moving, and to equalize the load over all of axles.
In the field of vehicle suspensions, it is further known to let at least one of the ends of an axle supporting spring free to slide relative to a supporting hanger in order to absorb the up and down motions of the axle supported by this spring. In this connection, reference can be made to U.S. Pat. No. 3,767,222 of 1973 and U.S. Pat. No 4,486,029 of 1984.
However, so far, no one seems to have ever thought of combining all these knowledges in a triple axle suspension in order to improve the efficiency and reliability of the same.
The object of the present invention is to provide a triple axle go suspension for use in a vehicle, which suspension is very simple in structure, very efficient to equalize the load over the three adjacent axles of the vehicle and very reliable in use.
The triple axle suspension according to the invention makes use of rigid beams to support the axles. It also makes use of equalizers and it is devised in such a manner that one end of each beam is free to slide within the adjacent supporting equalizer or hanger.
As aforesaid, the triple axle suspension according to the invention is intended to be used in a vehicle having a frame below which a front axle, a medium axle and a rear axle are mounted in a triple axle relationship.
It basically comprises, on each side of the vehicle
a front axle supporting beam having a front end pivotably connected to a first hanger projecting downwardly from the frame, and a rear end;
a first equalizer rockably mounted onto a second hanger projecting downwardly from the frame, the first equalizer having a front portion through which the rear end of the front axle supporting beam is slidably mounted, and a rear portion;
a medium axle supporting beam having a front end pivotably connected to the rear portion of the first equalizer, and a rear end;
a second equalizer rockably mounted onto a third hanger projecting downwardly from the frame, the second equalizer having a front portion through which the rear end of the medium axle supporting beam is slidably mounted, and a rear portion; and
a rear axle supporting beam having a front end pivotably connected to the rear portion of the second equalizer, and a rear end slidably mounted onto a fourth hanger projecting downwardly from the frame.
As it can be appreciated, this suspension is very simple in structure. This suspension is also efficient to equalize the load of any axle over all the axles of the triple axle suspension. When the axles are motorized, the suspension according to the invention may further balance the pulls exerted by the wheels supported by the axles between all of them.